The present disclosure relates to wind turbines, and in particular relates to the reduction of load caused by different moments acting on a wind turbine. Specifically, the present disclosure relates to a wind turbine including a rotor having a plurality of rotor blades and a main shaft, and a hub, wherein the hub and the main shaft are connected by hub bolts.
Wind turbines are of increasing importance as an environmentally safe and relatively inexpensive alternative energy source. The increased demand for an improved wind turbine performance has triggered efforts concerning an optimum adjustment of the rotor blades of the wind turbine with respect to a minimum load applied to the entire wind turbine. The rotor blades transform wind energy into a rotational torque or force that drives one or more generators which are rotationally coupled to the rotor through a gear box. Loading moments across wind turbine rotors result from vertical and horizontal wind shears, yaw misalignment and turbulence. Load applied to the entire wind turbine can be provided in form of a yaw moment which results in a force about a vertical axis of the wind turbine structure. Furthermore, a pitching moment of the turbine's wind rotor may induce bending moments into the main shaft of the rotor such that a plane in which the rotor blades rotate is tilted about an axis perpendicular to the vertical axis of the wind turbine.
Most wind turbines provide an adjustment of a pitch angle of the rotor blades. The pitch angle is the angle of the airfoil with respect to the incoming air flow wherein an adjustment of the pitch angle is performed about the airfoil axis.